Issue 14

M.

Merlin, Frattura

ed Integrità Str

utturale, 14 (20

10) 64-74; DOI

: 10.3221/IGF-ES

IS.14.07

M Al

icrostru -Cu san

ctural d mou

charact ld casti

erisatio ngs

n relate

d to ho

t tearin

g of

M En ma

attia Merlin gineering Dep ttia.merlin@u

artment, Univ nife.it

ersity of Ferr

ara, via Sarag

at 1, 44100

Ferrara (Italy )

4.8  6)%Cu ge analysis. erent Cu an on the hot ing solidific ctic liquid f served by m dominated entrations. ariation an ercially av area and d to heal op

STRACT . In estigated by realisation alloy comp luated. The ameter for ts of the cr croscopes, w sence of a zones cha croscope w antitative m luated and examined a YWORDS . A n foundry componen long time. ticularly alum sing the dev erimental po idification, fo idified. Unlik refore, the al e the materia ticles, and th solidus tem ually dendriti ume fraction id film and s presence of metry of the TRODUCTIO

this paper means of m of the castin osition and quantity o the crack he acks. The h hich show liquid film, racterised ere statistic icrostructur correlated t lloys. l-Cu alloys; practice th ts. Hot tearin Both ferrou inium alloy elopment of int of view [ llowing inter e pure metal loy consists l can be con en as a mush perature, wh c in shape). T of solid is a olid bridges, two contemp mould. Firs N

, the hot te icrostructu gs and thre of differen f the eutec aling pheno ot tear path ed that the in particular by the max ally analyse al paramete o the capac

aring behav ral examina e Al-Cu allo t pouring te tic phase a menon, in f s and surfa fracture su at higher c imum cros d by mean rs of percen ity of the eu

iour in Al-( tion and ima ys with diff mperatures vailable dur act the eute ces were ob rfaces were opper conc s-section v s of comm tage, mean tectic liquid

sand moul A dog-bon d Si content tearing beh ation is co lows into th eans of op by bridged Several sam d the micr ailable ima istribution en fractures

d castings w e pattern wa s were used aviour of th nsidered a e hot tear a tical and sca grain boun ples were al ographs fro ge analysis of the eutec caused by

as prelimin s employed . The effect e castings w very impor reas and cov nning elect daries and so drawn fr m the opt software. T tic phase w hot tearing

ary for s of ere tant ers ron the om ical he ere for

A B inv the the eva par par mi pre the

mi qu

eva the

Sand mould

casting; H

ot tearing; M

icrostructu

re; Image an

alysis.

K E

I N I par cau exp sol sol the stat par the (us vol liqu the geo

e occurrenc g is one of t s and non s. Great effo hot tears; var 1-4]. Hot tea dendritic and s, alloys grad of both a liqu sidered as a when the g en the mater he growth o pproximatel as has been orary pheno tly, there is

e of solidifi he most seri ferrous alloy rt has been ious authors ring is related intergranul ually transfor id and solid slurry at the h rains starts t ial is in the m f a hot tear o y 85-90%, an suggested by mena, which the contracti

cation defec ous solidifica s can suffer made over have contrib to the nucle ar paths insid m from a liq for a consid ighest temp o interact wi ushy state, ccurs in the d it propaga several autho operate insi on of the m

ts limits th tion problem the develop recent decad uted to this ation and de e the materi uid to a solid erable period eratures, beca th each other solid bridges last stage of tes either thr rs [5]. The g de the alloy d etal as it cha

e production s and, moreo ment of ho es to under phenomenon velopment o al, when the state over a of time dur use it is liqu , generating are formed solidification ough the fu eneration of uring solidif nges from a

and perfo ver, it has b t tears durin stand the pr from both f macroscopi metal has no certain temp ing casting. I id with some a sort of ske between neig in the mush lly liquid film hot tears is p ication and a liquid to a s

rmance of een known f g solidificat incipal varia a theoretical c fissures du t yet comple erature inter n this semi-s suspended s leton [1]. Ab hbouring gr y state, while or through rincipally du lso related to olid, creating

cast or a ion, bles and ring tely val; olid olid ove ains the the e to the an

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